Hot-air pipe for furnaces.



No. 629,095. Patented July I8, 1899.

I. STE'ARNS.

HUT AIR PIPE FOR FUBNABES. (Appliation filed 1m. 16, 1898.)

(No Model.)

Isaac Seamzs 1 ZZZ/ways.

" To all whom, it midi concern.-

' which the following is a specification, referjoints formed at the ends thereof for connect-.

, and of greater strength, and, further, in the "tion showing two of myimproved sections se- Umen PATENT om 1 SAMUEL S TEARNS,

HOT-AIR Pl PE' F for SAME PLACE.-

oRFu NAcEsQ SPECIFICATION torming part bf Letters ratntua'ceaoes; dated il'ulylSi, 1899.

u s ream use 16, 1398.

Be it known that I, ISAAC STEARNS, a citi zen of the United States, residing at Detroit,- in the county of Wayne and State of Michigan, have invented certain new and useful Improvements in Hot-Air Pipes for Furnaces, of

ence being had therein to the accompanying drawings. I

The invention consists in the construction of a hot-air pipe, and particularly in the constructi on of a section of such pipes and in the ing the two sections together, whereby the constructionof such sections is simplified and cheapened and the joint is made more secure construction, combination, and arrangement of various parts, all as more fully hereinafter. described. f i

In thedrawings, Figure 1 is a side elevacured together. Fig. 2isa sectional perspective viewthrough the meeting ends of two of my sections of piping engaged together. Fig. 3 isaperspective view of half of an inner wall, showing the manner of bending the metal in over the same. Fig. 4 is a vertical longitudinal section through onewall of a section of my hot-air pipe.

In the previous state of the art it is well known that it is desirable to usea doublewalled pipe for hot air-as, for instance, in furnacesand in such pipes they have here tofore been made in sections with interlocking joints upon the'meeting ends; but heretofore, so far as I am aware, there has not been made a pipe-section having a mortise-andtenon joint or a tongue-and-groove joint in which the tongue and the grooves were made of bends in the plates which form the inner and outer walls themselves. This I accomplish with my construction as follows:

The pipe-sections maybe made up in any desired length and are shown rectangular. The outer wall A may be made of simply a straight piece ofv metal bent into rectangular form, with a hook B at one end. The inner wall is preferably made in two pieces, as shown in Fig. 3, although it may be made of a single piece, with its ends connected tosaa11uta,12i.; (Nomudeld get-her, if desired. The inner war 0 has a one end the two bonds 0. b, which formthe lateral substantially horizontal offset D and the substantially vertical tongue E. In makingthe pipe from the sheets provided with these bends the metal, of course, is split at thecorners, asv plainly shown in the drawings. The tongue E engages with the hook B,-as shown in Fig. 4. At the opposite end the metal of the inner wall is bent to form first a substantially horizontal ofiset c and then the substantially vertical trough or groove 61 and the hook e, the width of the oftset and the groove being the same as that of the ofiset D at the other end, so as to make the desired opening. between the two walls,

the hook 6 being engaged with the end of the outer wall, as plainly shown in Fig. 4. This forms a double-walled pipe, in effect consisting of an outer wall and an inner wall, the ends of the walls being integrally connected one with the other-that is, without the interposition of a bridge piece or strip at the end, as has heretoforesometimes been used. The offsets D and c'abut when the sections are in place and are apertu red in line, so that there may be the usual air circulation in the hollow walls of the pipe. The corners of the tongues, which'project beyond the ofiset D, are slotted, so that these tongues letteredF in Fig. 4:) may be bent inward somewhat to engage in the grooves d and form what I call flexible tongues. tongues flexible and cutting them away slightly at the corners I am enabled without any shaping of the outer wallwhatever to press them in slightly, so that the tongue of one section will engage into the groove ,d of an adjoining section. By making these tongues and grooves of the proper proportion to each other I am enabledto obtain practicallya tight fitat the joints, and in addition to the friction which a tongue-and-groove joint would have I get the friction due to the spring efiect of the tongues. By having offsets D at the ends of the pipesections I By making these strengthen them materially, so that thereis no liability of'bending or denting them in handling or shipping, as would be the case in the event that the offsets were down some sections. Then as the tongue at the other end is entirely flexible if it should be bent in shipping or in handling it is very readily straightened or may be pushed back into shape by the hands of'the operator, so thatit may be engaged with. the groove when the parts are brought together. I t will be observed that by this construction I make the outer slots and the end slots of the section from the same piece or" metal and at the same time form therein a tongue-and-groove joint.

What I claim as my invention is A pipe-section of the vcharacter described comprising a plate having one edge bent at right angles forming a horizontal seat pro- ISAAC STEARNS.

Witnesses:

M. B. ODOGHERTY, OTTO F. BARTH L. 

